Carbon paper



Dec. 19, 1939. K. OHASH] 2,183,580

CARBON PAPER Filed May 25, 1937 Inventor: ALLAN K. OHASHI Attorneys Patented Dec. 19, 1939 UNETE STATES FATENT @FFECE '7 Claims.

pleyed basically mixtures of Waxes, oils "K substances, and coloring matter. By Way of carnauha wax, a mineral oil or other on compatible with the was, and carbon black, is

eat deal of difficulty is experienced in Ohtaining good adhesion of the color composition to the paper. The color coz 'oosition ltendcncy to crack and break 0 1 the ordinary use kling and s rp bending of the sheets not only v n c :acted by the keys of the typewriter but also d1 ing handling. The lighter weight carbon sheets have a distinct tendency to form he impressions on the copies, which is pr;-

due to unavoidable creasing and wrinkling iii; insertion of the same with other sheets the type. iter. There is also a distinct tendency for carbon to curl. This particularly true 0. Weights, and all Weights will curl at least extent during damp Weather. Curling carson papers causes a great deal of incone ience in handling and results in a considerloss of time. All carbon papers lacking rength to a certain degree this is of the lighter weights.

. objects will become apparent as the "cation proceeds and upon reference to the ig, in which e a cross section shown bro en and .ably enlarged of an unirhp-regnateo-uhted sheet; a similar section having the color 'ed to one surface in a more or and more particularly to the drawing, in ich embodiment of the invention is disclosed for the purposes .of illustration, at i9 is shown an unimpregnated-uhcoated base sheet. No attempt has been made to show relative proportions. A coating of a solid plastic color-containing ""c csition H is shown applied to the surface of sheet iii.

The color-containing material i may be applied in a no mal Way which results in a substanti? degree of impregnation of the sheet is illustrated diagrammatically at 53. The composition ii does not orrnally fill all of the voids in and between the bres or, in other Words, the ln1pregnation is not normally such as to completely pregnate the paper it adjacent the surface i i.

According to this invention, impregnation of sheet i6 is cemcleted through the surface is by the tion of a composition which is elastic, resilient, Water resistant and preferably waterproof, a d which possesses a desired degree of fibre lending ability and good im regnation pro erties. i e composition should be solid a temperatures and after evaporation or of any solvent present.

I prefer to use as the impregnating material a cellulosic plastic dope, of which the various con mercial cellulose nitrate and cellulose acetate lecquers are representative. Besides the cellulose esters, other generated cellulosic ccrnpoiohs as the cellulose others, ethyl cellulose, and eutyi cellulose, may used. in association with appropriate plastlcizir agents and solvents to form a dope or lacquer that is fluid and applicahle bv conventional coating methods. The dope, te containing a cellulose ester or other cellulosic substance as a base, should have a suificient amount of plasticizer or softener so that the dope when dried Wll not be characteri by stiffness, such as is "esent. for instance, in collcdioh fr" and so at the paper unpregnated therein i ill have de d degree of elasticity and resiliency, out at the more body. The cellulosic time W..1l have composition Will cent between th ,s of the pap on of the dope is substantially one .i. inc section through the surface though is possible to leave very tr film on such surface if desired,

hit 3 to be made by the striking Inasmuch as the various cellulosic plastic dopes and the various carbon and other color compositions are as a rule compatible and miscible with each other and are at least to a certain extent soluble in each other, the dope may, if impregnation therewith is carried out to a sufiicient extent, penetrate through into the carbon composition and aid in holding the same to the surface l2.

After application of the dope, its volatile solvent is permitted to evaporate and when dried the impregnated sheet is ready for use.

The cellulosic plastic dope may carry any of the usual coloring matters, such as pigments, dyes and/or lakes for ornamentation or identification purposes, and as a result the surface I4 may be given a uniform color or any color combination,

The finished carbon paper possesses more body without material increase in thickness, whether it is of light, medium or heavy weight, and any increase in thickness is determined by the amount of dope applied.

Inasmuch as the carbon paper possesses more body, which is furnished by a composition having the desired elastic and resilient properties, the tendency to curl and to wrinkle, crinkle or sharply bend during use, either as a result of handling or of striking with the typewriter keys, is greatly reduced, without a reduction in the desired useful properties of such material. As a consequence, a great deal of time is saved in handling of the sheets with improvement in quality of copies and the tendency of the carbon composition to chip or crack off is reduced resulting in a longer useful life for the carbon paper compared to its useful life prior to impregnation with the dope.

The finished carbon paper has a greater tensile strength in view of the cementation of the fibres of the paper sheet, resulting in a greater resistance to tearing. In View of the increased body, the tendency of the light weight carbons to form tree-like impressions is substantially absent.

In view of the substantially complete impregnation of the paper from opposite sides with relatively non-hygroscopic materials,the cellulosic or other moisture-proofing composition on the one side and the color-carrying marking composition on the other,the tendency exhibited in ordinary carbon papers to respond to changes in relative humidity is removed.

The carbon paper may be manufactured in the ordinary way by any of the ordinary processes after which the uncoated surface is impregnated with cellulosic dope or equivalent waterproofing and impregnating composition as above indicated. It is, however, possible to impregnate simultaneously from opposite sides of the base with the respective impregnating materials, or otherwise.

I am aware of the fact that it has been proposed to form a manifold sheet from bibulous paper impregnated from one side by a non-drying ink and coated on the reverse side by a thin coating of collodion which serves to prevent the ink from exuding from the back of the sheet. It has also been proposed to apply a pyroxylin solution on one or both faces of a typewriter ribbon to act somewhat as a filter for the purpose of regulating the amount of ink transferred to the paper in the typing operation. The carbon paper of my invention diifers from the manifold sheet of the prior art above mentioned in that a normally solid color composition is applied to the relatively thin and hard non-bibulous paper customarily employed in forming carbon paper. When the water resistant impregnating composition is applied after the color composition is applied, as preferred, my carbon paper has the further difference and advantage that the impregnating composition penetrates into the zone occupied by the color composition with the result that the color is more firmly held onto the paper base, thereby preventing breaking or chipping off under the impact of the type, as happens at present to a more or less degree. The differences in purpose and result between my carbon paper and the typewriter ribbon of the prior art are obvious and would not appear to require discussion.

Having described my invention, .it is obvious that many modifications may be made in the same within the scope of the claims without departing from the spirit thereof.

I claim:

1. A process for making manifold sheets comprising coating and impregnating a sheet of paper on and through one of its surfaces with a suitable normally solid carbon-containing color composition and then impregnating said sheet through its other surface with a plasticized cellulose nitrate composition which solidifies on standing, to form a highly flexible impregnation.

2. A process for making manifold sheets comprising coating and impregnating a sheet of paper on and through one of its surfaces with a suitable normally solid carbon-containing color composition and then impregnating said sheet through its other surface with a plasticized cellulose acetate composition which solidifies on standing to form a highly flexible impregnation.

3. A process for making manifold sheets comprising coating and impregnating a sheet of thin non-bibulous paper on and through one of its surfaces with a suitable normally solid carboncontaining color composition and then impregnating said sheet through its other surface with a plastic cellulosic composition which solidifies on standing to form a highly flexible impregnation.

4. A manifold sheet comprising a sheet of thin non-bibulous paper coated and impregnated on and through one surface with a suitable carboncontaining color composition and impregnated through its other surface with a pigment-containing plasticized cellulosic composition which is compatible with the color composition and flexibile in its solidified state, said pigment im- 4 parting to said other surface a characteristic appearance, said sheet being further characteriZed by its freedom from tendency to curl and form tree-like impressions on copies, and further characterized by ability to produce sharp impressions even when used in producing a relatively large number of copies simultaneously.

5. A manifold sheet comprising a thin nonbibulous paper base having on its face a coating of a normally solid color composition and having on its back a coating of a plasticized cellulosic composition, said cellulosic composition being compatible with the color composition and flexible in its solidified state, said sheet being further characterized by its freedom from tendency to curl and form tree-like impressions on copies, and further characterized by ability to produce sharp impressions even when used in producing a relatively large number of copies simultaneously.

6. A manifold sheet comprising a thin nonbibulous paper base having on its face a coating of a normally solid color composition and having on its back a coating of a plastioized cellulose nitrate composition, said cellulose nitrate composition being compatible with the color composition and flexible in its solidified state, said sheet being further characterized by its freedom from tendency to curl and form tree-like impressions on copies, and further characterized by ability to produce sharp impressions even when used in producing a relatively large number of copies simultaneously.

7. A manifold sheet comprising a thin nonbibulous paper base having on its face a coating of a normally solid color composition and having on its back a coating of a plasticized cellulose acetate composition, said cellulose acetate composition being compatible with the color composition and flexible in its solidified state, said sheet being further characterized by its freedom from tendency to curl and form tree-like impressions on copies, and further characterized by ability to produce sharp impressions even when used in producing a relatively large number of copies simultaneously.

ALLAN K. OI-IASHI. 

